The present invention relates generally to the field of guide wires for advancing intraluminal devices, such as stent delivery catheters, balloon dilatation catheters, atherectomy catheters and the like, within body lumens. The present invention is particularly directed to a guide wire having a medical device, such as an embolic filter, laser or ultrasonic cutting device, atherectomy device and the like, attached near its distal end for delivering the medical device into an area of treatment in a body lumen.
A variety of non-surgical interventional procedures have been developed over the years for opening stenosed or occluded blood vessels in a patient caused by the build up of plaque or other substances on the wall of the blood vessel. Such procedures usually involve the percutaneous introduction of an interventional device into the lumen of the artery, usually through a catheter. In typical PTCA procedures, a guiding catheter or sheath is percutaneously introduced into the cardiovascular system of a patient through the femoral artery and advanced through the vasculature until the distal end of the guiding catheter is in the ostium of the desired coronary artery. A guide wire is positioned within a lumen of a dilatation catheter and both devices are introduced through the guiding catheter to its distal end. The guide wire is first advanced out of the guiding catheter into the patient's coronary vasculature and is directed across the arterial lesion. The dilatation catheter is subsequently advanced over the previously advanced guide wire until the dilatation balloon is properly positioned across the arterial lesion. Once in position across the lesion, the expandable balloon is inflated to a predetermined size with a radiopaque liquid at relatively high pressures to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile so that the dilatation catheter can be withdrawn from the patient's vasculature and the blood flow resumed through the dilated artery. As should be appreciated by those skilled in the art, while the above-described procedure is typical, it is not the only method used in angioplasty.
In the procedures of the kind referenced above, abrupt reclosure may occur or restenosis of the artery may develop over time, which may require another angioplasty procedure, a surgical bypass operation, or some other method of repairing or strengthening the area. To reduce the likelihood of the occurrence of abrupt reclosure and to strengthen the area, a physician can implant an intravascular prosthesis for maintaining vascular patency, commonly known as a stent, inside the artery across the lesion. The stent is crimped tightly onto the balloon portion of the catheter and transported in its delivery diameter through the patient's vasculature. At the deployment site, the stent is expanded to a larger diameter, often by inflating the balloon portion of the catheter. Alternatively, a self-expanding stent could be expanded at the deployment site.
Another procedure for treating a stenosed region of an artery is laser angioplasty which utilizes a laser to ablate the stenosis by super heating and vaporizing the deposited plaque. Atherectomy is yet another method of treating a stenosed blood vessel in which cutting blades are rotated to shave the deposited plaque from the arterial wall. A vacuum catheter is usually used to capture the shaved plaque or thrombus from the blood stream during this procedure.
The above non-surgical interventional procedures, when successful, avoid the necessity of major surgical operations. There is one common problem associated with all of these non-surgical procedures, namely, the potential release of embolic debris into the bloodstream that can occlude distal vasculature and cause significant health problems to the patient. For example, during deployment of a stent, it is possible that the metal struts of the stent can cut into the stenosis and shear offpieces of plaque which become embolic debris that can travel downstream and lodge somewhere in the patient's vascular system. Techniques have been developed to trap the emboli which include the placement of a filter or trap downstream from the treatment site to capture embolic debris before it reaches the smaller blood vessels downstream.
These above-mentioned devices can be placed within a body vessel usually in one of two ways. The device can be deployed into the area of treatment by advancing the device along a guide wire using over-the-wire techniques.
Alternatively, the device can be directly attached to the guide wire to allow the device to be placed in the patient's vasculature as the guide wire is moved into place by the physician. Once the guide wire is in proper position, the physician can operate the device to perform the desired procedure within the vasculature. The guide wire also can be used by the physician to deliver other interventional devices, such as a balloon angioplasty catheter or a stent delivery catheter, into the area of treatment.
Because of the environment that guide wires are used, and the purpose they serve, it is desirable to have several basic features for most, if not all, guide wires. The guide wire must be able to navigate and advance within the lumens of a patient, and come into contact with delicate tissue. For this reason, the guide wire usually requires a soft, flexible distal tip which can be manipulated without causing injury to the vessel walls. It also must be sufficiently maneuverable to reach the required destination, which requires stable torsional characteristics, and a rigid proximal shaft that can be pushed to advance the guide wire. This is particularly true when a medical device is attached near the distal end of the guide wire. Often, these characteristics are difficult to achieve, since one feature tends to negate the other. It is also desirable for the outer diameter of the guide wire to fit properly within the inside diameter of the lumen within which it is disposed.
Conventional guide wires for use in angioplasty, stent delivery, atherectomy and other vascular procedures generally comprise an elongated core member with one or more tapered section near the distal end and a flexible body member such as a helical coil disposed about distal portion of the core member. A shapable member, which may be the distal end of the core member or a separate shapable ribbon secured to the distal end of the core member enables the physician to shape or curve the tip as needed for maneuvering purposes. Torquing means are provided on the proximal end of the core member to rotate, and thereby steer, the guide wire while it is being advanced through the patient's vasculature. The tip of the guide wire should be highly flexible and a traumatic so as not to damage or perforate the vessel while the portion behind the tip should be increasingly stiff to better support the medical device attached to the guide wire.
Further details of guide wires, and devices associated therewith for various interventional procedures can be found in U.S. Pat. No. 4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams et al.); and U.S. Pat. No. 5,345,945 (Hodgson et al.) which are hereby incorporated by reference in their entirety.
There can be some problems associated when the medical device is directly attached to the guide wire. For example, a shockwave (vibratory motion) can be developed during the exchange of the delivery catheter or other interventional device on the guide wire which will travel along the length of the guide wire and possibly ajar the deployed medical device. A shockwave can possibly result in trauma to the wall of the blood vessel since the medical device will experience the shock and will transmit that force to the vessel wall in a scrapping action. These types of occurrences are undesirable since they can cause trauma to the vessel which is detrimental to the patient's health and/or could possibly cause the medical device to be displaced within the vessel.
What has been needed is a guide wire for use in the coronary and the peripheral vasculatures, particularly the carotid arteries, which is capable of acting as a "shock absorber" to absorb some of the energy which may be generated during the exchange of medical devices over the guide wire or by some external source. Such a guide wire would thus reduce the amount of vibratory motion which can travel over the length of the guide wire and prevent the vibration or shock from acting on the medical device attached to the guide wire core. As a result, the medical device should not move significantly or cause damage to the vessel wall since much of the energy transmitted along the length of the guide wire will be intercepted before reaching the medical device. The present invention disclosed herein satisfies these and other needs.